Bangladesh has banned three Islamic charities from working with Rohingya refugees, a Bangladeshi lawmaker said on Thursday, amid concerns displaced Muslims in camps along its border could be radicalised.

Mahjabeen Khaled, an MP from the ruling Awami League, said the international charities Muslim Aid and Islamic Relief, and Bangladesh-based Allama Fazlullah Foundation, had been blacklisted from the Rohingya refugee camps in southernmost Cox's Bazar district.

Khaled, who sits on the parliamentary standing committee on foreign affairs, said no specific allegations had been levelled at the charities.

But authorities were “scrutinising and screening” all aid agencies wanting to contribute to the massive relief effort in Cox's Bazar, where more than half a million refugees had fled to squalid camps since August.

“We want to monitor who is giving aid, and why, for security reasons. Who are funding them, and what they are going to do with the money?” Khaled told AFP.

“They [Rohingya] are vulnerable. A lot can be done with this Rohingya people. We want to be careful,” she said, adding it would be “easy” to lure the refugees to militancy.

Waseem Ahmed, a director of Islamic Relief, said any allegations of misconduct by the charity were “baseless and misguided”. “Since we are still awaiting approval from the government and haven't started any projects yet in the camps, it would be completely unwarranted to tag us with any activities that we haven't conducted,” he said.

Bangladesh has heavily curtailed access to the Rohingya camps in recent years, but eased restrictions last month after more than 520,000 new refugees poured across the border. The government's NGO Affairs Bureau approved 30 local and global aid groups to meet “emergency needs” in the overwhelmed camps, which already housed about 300,000 Rohingya before the latest influx.

Before that, just four international charities — including Doctors With Borders (MSF) and Action Against Hunger (ACF) — were permitted to operate in the sensitive border district.

Khaled said Muslim Aid had also been banned from working in the refugee camps in 2012, when tens of thousands of Rohingya Muslims fled a separate surge of violence in neighbouring Myanmar.

Bangladesh authorities are reluctant to discuss their reasons for curbing access to the camps, but fears prevail that anger among the displaced Rohingya could be exploited by extremist networks.

Bangladesh is fighting its own battle against homegrown radicals, who have claimed responsibility for the brutal murder of bloggers, activists and foreigners in recent years. Even those charities given the green light last month can only work for two months, and must restrict activities to providing healthcare, sanitation facilities and shelter for the Rohingya.